The ‘Terror of the Tiny’: Contagion and the Transformation of Nineteenth-Century Literature Why do things that physically underwhelm us emotionally overwhelm us? Why and when is power disproportionate to presence? What does it mean to be dominated by and afraid of things we (almost) cannot see? This dissertation seeks to provide partial answers to these questions by exploring the association between the development of contagion theory and representations of the “terror of the tiny” in nineteenth-century and early twentieth-century British and American texts. A fear of small things is hardly mysterious if such creatures are always already posited as simply disease-causing agents. However, as this dissertation will show, “the tiny” encompass much more than germs, and thus the fear these creatures inspire is far more complex and diverse in its origins and influences. Through analysis of depictions of contagion and infectious illness that occur alongside anxiety over the small things in literature, I will show how the rise of germ theory impacted the national psyche by undermining scientific as well as cultural, political, and socio-economic beliefs. This project further distinguishes itself from other critical analyses of illness and literature via its focus on genre, specifically how certain modes of characterization and representation of infectious diseases and epidemics that are common across different novels, stories, non-fiction prose, etc., effectively function to challenge the conventional categorization of those works of literature. Similar depictions and treatments of contagion in fiction, I argue, not only enable these separate pieces to individually transcend their ‘home’ genres (of detective fiction, sensation novel, ghost story, etc), but also, in some cases, leads them collectively to inaugurate an entirely new generic category. These new and/or transformed genres, I further contend, ultimately reflect a desire, if not need, to rethink what constitutes England and Empire, Great Britain and America, “child” and “adult”, and, indeed “big” and “small” given the omnipresent threat of infectious disease.